An epidemic of tuberculosis occurred in a community of Aboriginal Canadians during the period 1987-89. Genetic and epidemiologic data were collected on an extended family from this community, and the evidence for linkage to NRAMP1, a candidate gene for susceptibility to mycobacterial diseases, was assessed. Individuals were grouped into risk (liability) classes based on vaccination, age, previous disease, and tuberculin skin-test results. Under the assumption of a dominant mode of inheritance and a relative risk of 10, which is associated with the high-risk genotypes, a maximum LOD score of 3.81 was observed for linkage between a tuberculosis-susceptibility locus and D2S424, which is located just distal to NRAMP1, in chromosome region 2q35. Significant linkage was also observed between a tuberculosis-susceptibility locus and a haplotype of 10 NRAMP1 intragenic variants. No linkage to the major histocompatibility-complex region on chromosome 6p was observed, despite distortion of transmission from one member of the oldest couple to their affected offspring. The ability to assign individuals to risk classes was crucial to the success of this study.

The prevalence of and risk factors for attempted suicide and suicidal ideation were examined with a survey of 99 Inuit, aged 14-25 years, residing in a community in Northern Québec. A total of 34% of survey respondents reported a previous suicide attempt, and 20% had attempted suicide more than once. A suicide attempt had resulted in injury in about 11% of those surveyed. The prevalence of suicidal ideation was also very high: 43% of subjects reported past thoughts of suicide, and 26% had had suicidal thoughts during the month before the survey. Risk factors for suicide attempts included male gender, having a friend who had attempted or committed suicide, a history of being physically abused, a history of solvent abuse, and having a parent with an alcohol or drug problem. Protective factors included a family history of having received treatment for a psychiatric problem, more frequent church attendance, and a high level of academic achievement. While individuals in the community who are at high risk for suicide can be targeted for preventive measures, the high prevalence and effect of family problems on likelihood of suicide attempts indicate the need for family- and community-based approaches.

Suicide prevention programs can be targeted at youth who are using substances, particularly solvents, cocaine, and alcohol, have psychiatric illness, and have experienced recent negative life events. Involvement in church or other community activities may reduce the risk for suicide. Consideration of gender differences may allow more precise identification of those at risk for attempted suicide.

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The existence of associations between spouses for the presence of psychiatric disorders, either similar or different, has significant implications for both clinicians and researchers. Future research should aim at exploring the aetiological mechanisms of these associations.